Rotation quenches in trapped bosonic systems

TL;DR

This paper explores the out-of-equilibrium dynamics of rotating bosonic systems in anharmonic traps, revealing how symmetry and quench size influence angular momentum transfer, vortex formation, and density evolution.

Contribution

It provides a comparative analysis of mean-field and many-body dynamics in asymmetric traps under rotation quenches, highlighting the role of symmetry and quench magnitude.

Findings

Rotation quenches have minimal effect in symmetric traps due to angular momentum conservation.

Asymmetric traps allow for angular momentum exchange, leading to complex dynamics.

Large quenches cause divergence between mean-field and many-body system behaviors.

Abstract

The ground state properties of strongly rotating bosons confined in an asymmetric anharmonic potential exhibit a split density distribution. However, the out-of-equilibrium dynamics of this split structure remain largely unexplored. Given that rotation is responsible for the breakup of the bosonic cloud, we investigate the out-of-equilibrium dynamics by abruptly changing the rotation frequency. Our study offers insights into the dynamics of trapped Bose-Einstein condensates in both symmetric and asymmetric anharmonic potentials under different rotation quench scenarios. In the rotationally symmetric trap, angular momentum is a good quantum number. This makes it challenging to exchange angular momentum within the system; hence, a rotation quench does practically not impact the density distribution. In contrast, the absence of angular momentum conservation in asymmetric traps results in more complex dynamics. This allows rotation quenches to either inject into or extract angular momentum from the system. We observe and analyze these intricate dynamics both for the mean-field condensed and the many-body fragmented systems. The dynamical evolution of the condensed system and the fragmented system exhibits similarities in several observables during small rotation quenches. However, these similarities diverge notably for larger quenches. Additionally, we investigate the formation and the impact of the vortices on the angular momentum dynamics of the evolving split density. All in all, our findings offer valuable insights into the dynamics of trapped interacting bosons under different rotation quenches.